Steel is one of modern society’s core pillars. With an ever-developing infrastructure industry, steel sits at the helm as one of the most significant engineering and construction materials. However, the steel industry is a major contributor to the global climate crisis. Research by the Carbon Brief shows that just 533 conventional steel plants across the world are responsible for 9 percent of total carbon dioxide emissions due to the usage of fossil fuels- predominantly coking coal in the manufacturing process.
The Age of Steel
From the 12th century steel quickly replaced iron as a primary building material. Compared to other forms of iron, steel has higher strength and fracture resistance. It is more economical and is corrosion and oxidation resistant. Its excellent tensile strength has rendered it irreplaceable in the construction industry. During the second industrial revolution, steel almost completely replaced iron. Today, steel is so extensively used and known for its strength, durability and efficiency that it has become a hallmark for its properties. Movie titles like “Superman: Man of Steel” and “Real Steel” reiterate this fact.
Steel is regarded as the backbone of the modern infrastructure industry. Steel skeletons support skyscrapers, stadiums, airports and bridges. Construction materials like bolts, nails and screws are made of steel. Steel is used to build vehicles like ships, cars, trains as well as smaller articles like cutlery, guns, appliances, jewellery and parts of space crafts. Various grades of steel are used to furnish reinforcement bars and meshes in reinforced cement concrete constructions.
Today, the steel industry is among the top three global producers of carbon-di-oxide. Nearly 2 billion tons of high-strength steel are manufactured yearly for bridges, buildings, roads and railways. According to the World Steel Organization, for every ton of steel produced in 2018, 1.85 tons of carbon-di-oxide were released globally, accounting for 8 percent of worldwide carbon dioxide emissions. Keeping in mind the significance of steel and its associated materials, the industry is a prime candidate for decarbonization.
Steel is produced after processing naturally occurring iron ore. The raw materials required for steelmaking are mined and transformed into steel using either of two processes- blast furnace/ basic oxygen furnace or the electric arc furnace (EAF). The blast furnaces that melt the iron ore consume vast quantities of coal. Here, carbon in the coal(coke) removes the oxygen from the iron ore.
Fe2O3(s) + 3 CO(g) → 2 Fe(s) + 3 CO2(g)
Chemical reaction in the blast furnace
CaCO3(s) → CaO(s) + CO2(g)
Additionally, other sources of carbon-di-oxide emissions within the industry include the Lina-Donawitz steelmaking or basic oxygen steelmaking, calcination and the hot blast. The blast furnace exhaust gas, a by-product of the blast furnace contains large amounts of carbon monoxide which is burnt for electricity furthering greenhouse gas emissions.
A joint venture by Swedish steelmaker- SSAB, iron ore miner- LKAB and energy company- Vattenfall – HYBRIT (Hydrogen Breakthrough Ironmaking Technology) has introduced the world to its first carbon-free steel. This “green steel” runs on zero carbon and is an environmentally conscious transition towards reducing the global carbon footprint.
HYBRIT aims to replace coke and carbon with green hydrogen and renewable electricity in the removal of oxygen from iron in the blast furnace as well as in the production of iron pellets which form a major raw material in the production of steel.
It claims that by eliminating the use of fossil fuels in the steelmaking process, HYBRIT can reduce Swedish greenhouse gas emissions by 10 per cent.
Hydrogen does not emit greenhouse gases when burned and can be made with natural gas or by renewable energy consuming methods. This hydrogen is then used instead of coal to remove the oxygen from the iron ore, thereby eliminating the need for carbon.
The green steel which is now in its commercial testing phase with Volvo can herald a new, climate-conscious change in the steelmaking industry. The venture aims to hit the market by 2026 with accessible green steel for all.
Following the footsteps of decarbonized steel pioneer HYBRIT, steel manufacturing giants from across the world are taking on more environmentally friendly initiatives. Boston Metal aims to curb emissions by expanding its efforts in electrolysis. Luxembourg-based ArcelorMittal is implementing its Hydrogen DRI in a demonstration plant in Germany. Japanese multinational company- Mitsubishi Heavy Industries aims to trial the green hydrogen method in its 250,000-ton steel plant in Austria. Companies like Tata Steel, Aço Verde do Brasil, Emirates Steel, Nucor, Thyssenkrupp Steel and Nippon Steel Corporation have begun their transition towards making greener steel.
This move to create and sustain lesser greenhouse gas emissions from the industry with one of the largest carbon footprints in the world is a big step towards battling the climate crisis. Not only does it motivate manufacturing giants to head in a more conscious direction, but it also brings in hope for other industries to go carbon-free.
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